Mixtures and chromatography

• What is a mixture?

  A combination of two or more substances that are not chemically bonded together
• What are two examples of mixtures?

  Crude oil and air
• What happens to each property of each substance in a mixture?

  They remain unchanged
• What are the physical processes which separate mixtures?

  Filtration, simple distillation, chromatography, crystallisation, fractional distillation
• Physical separation processes do not…

  Involve chemical reactions and no new substances are made
• explain the chromatography practical

  • draw a line near bottom of the sheet of filter paper in pencil. it is insoluble so wont dissolve in solvent.
  • add spot of ink to line and place sheet in beaker of solvent.
  • make sure ink isn’t touching solvent so it doesn’t dissolve.
  • put a lid on top to stop it evaporating
  • solvent seeps up paper, carrying ink with it.
  • each different dye in ink will move up at different rates. separate out.
  • when solvent has nearly reached the top, take it out the beaker and leave to dry
  • end result is pattern of spots - chromatogram